Question for our Canadian members, especially those from the western provinces and territory.

I travel in Canada often, mostly in BC and the Yukon. Seems no matter what kind of deal I make with my cell company and despite my best efforts to limit the use of my phone, I end up with substantial additionial charges when traveling in Canada. I am considering buying a TracPhone or other similar disposable phone the next time I'm up north. I will appreciate any advice or info I can get from those who have experience using such phones in Canada. How's coverage? Cost to buy/use? Does the time expire or roll over indefinately? Good place to buy? Canadian Tire?

Thanks for your help.